1. Field of the Invention
The present invention relates to a power source apparatus for vehicles having a first battery for supplying a current to a load of a start-up system and a second battery for supplying a current to a load of a non-start-up system and, in particular, to a power source apparatus capable of maintaining the first battery in a satisfactorily charged condition so that an engine may be started smoothly.
2. Description of the Related Art
Conventionally, a power source apparatus has a single three-phase alternating current generator and a single battery. An alternating current generated by the alternating current generator is rectified by a three-phase full-wave rectifier to produce a direct current output. "Alternating current" and "direct current" will be abbreviated hereinafter as "a.c." and "d.c.", respectively. The battery is charged by this direct current and supplies a current to the load of a start-up system, such as a starter motor, and other loads of a non-start-up system connected in parallel with the battery.
In the above-described conventional power source apparatus for vehicles, however, the battery runs out of electricity where a large current is dissipated carelessly when the engine is not in operation or where a current continues to be supplied from the battery to the electric load when electric generation of the a.c. generator is insufficient, for example when involved in a traffic jam. A problem occurs if the engine is not running or stops running and the battery has run out of electricity because the engine cannot be restarted.